# Aqueous Extracts of Carica papaya Embryogenic Callus Kill Entamoeba histolytica Trophozoites and Orally Protect against the Development of Amoebic Liver Abscesses in Hamsters

## TL;DR

Aqueous extracts from Carica papaya callus cultures show strong anti-amoebic effects in lab and animal studies, potentially offering a natural treatment for amebiasis.

## Contribution

The study demonstrates that Carica papaya callus extracts can effectively kill Entamoeba histolytica and prevent liver abscesses in hamsters.

## Key findings

- Pcc-KETc7-AE and Pcc-WT-AE extracts reduced E. histolytica trophozoite viability in vitro, with Pcc-KETc7-AE matching metronidazole's efficacy.
- Oral treatment with Pcc-WT-AE prevented amoebic liver abscesses in 80% of hamsters, similar to metronidazole.
- Pcc-KETc7-AE reduced lesion severity but did not prevent abscess formation in vivo.

## Abstract

This study evaluated the anti-amoebic properties of aqueous extracts of two Carica papaya callus clones, Wild Type (Pcc-WT-AE) and KETc7-expressing (Pcc-KETc7-AE) clones, in in vitro and in vivo assays.

E. histolytica trophozoites cultures were exposed for 24 h to varying concentrations of the C. papaya aqueous extracts, and their viability and IC50 determined by MTT assays. In in vivo studies, golden hamsters were infected intraportally with E. histolytica trophozoites and orally treated with the C. papaya aqueous extracts for 7 days. The animals were sacrificed on day 8, and the development of ALA was recorded. Comparisons were made against metronidazole (MTZ).

Both extracts statistically reduced trophozoite viability at 24 h in a dose-dependent manner in vitro. Pcc-KETc7-AE showed activity to the same extent as MTZ (IC50 36.08 µg/ml vs. 33.54 µg/ml, respectively), whereas Pcc-WT-AE exhibited less efficient but significant activity (IC50 113.4 µg/ml). Cell death analysis indicated that both extracts killed trophozoites by necrosis. In vivo studies showed that oral treatment with Pcc-WT-AE (4 and 8 mg/dose/hamster) completely prevented ALA development in 80% of animals, comparable to the effect of MTZ. In contrast, oral treatment with Pcc-KETc7-AE did not prevent lesions, but statistically reduced hepatomegaly, ALA size, and necrotic areas in tissue sections.

The aqueous extracts from C. papaya embryogenic callus cultures analyzed here exhibit potent, yet variable, anti-E. histolytica activity in both in vitro and in vivo studies. The activity was nearly as effective as MTZ suggesting their potential use as a new, natural and safe oral treatment for amebiasis.